In order to hold objects to be worked upon it has been suggested in the prior art that one apply a vacuum to a table having openings in its surface which will create suction forces on the object. Various types of structures within the prior art have been suggested such as shown by U.S. Pat. Nos. 3,042,356 and 3,741,116.
In the earlier of these an apparatus is described where an upper plate having a plurality of holes therethrough is placed over a corrugated mat made of a flexible material having passages within it leading to slots communicating with a passage open to a port through a support plate thereunder. There is no suggestion in this reference that the structure could support heavy work without obstruction of the fluid flow path of the sandwiched corrugation or that by sizing openings through the outer plate with regard to the outlet passage for the corrugations one could obtain the results desired with much more practical vacuum apparatus.
In the more recent patent the support table is made of sheets separated by a honeycomb core. The upper sheet is perforated and each core passage of the honeycomb is connected. Therefore, a vacuum drawn through the bottom plate evacuates the entire core in obtaining a negative pressure at the surface for drawing and holding work thereon.